Speakers slipping on speaker stands


I find that my speakers slip around a bit more than I'm comfortable with on the platform of my speaker stands. Is there anything I can do to make the placement more secure, without doing anything permanent to my speakers or stands? They haven't really come close to falling off but they do slide around and spin a bit when I touch them.

Any advice?
insomniac99
Post removed 
A little unsightly, but here in shaky California a must:

I use black bungie straps from the top of the speakers to under the stand's platform to hold down my speakers to their stands.
I second weather stripping..cheap and available at your nearest "true value", use that for now to get them stable and tweak later
Out of all these suggestions, I agree with the Blu-tack. This works amazingly well. It is often difficult for me to get the speaker off if it has been sitting on it for a while. Try Fun tack or similiar putty product. Any office supply or drugstore carries it for less than 2 bucks.
Post removed